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New Member

OSPFv3 IPv6

Hi,

Just after some clarification on how to "correctly" configure OSPFv3.

Goal - Configure OSPF to only advertise "connecting" link addresses between our routers and router loop addresses, and to then use iBGP to advertise/redistribute all customer routes between our routers.

- Is it best practice to configure the router loopbacks as /64's and then configure "ipv6 ospf network point-to-point" under the loopback so that the IPv6 address is advertised as a /64 and not as /128?

- There is no need to have "passive-interface default + no passive-interface" under address-family ipv6 unicast as you enable OSPFv3 under each Interface?

Thanks in advance for any comments/suggestions.

Everyone's tags (2)
3 REPLIES

Re: OSPFv3 IPv6

John,

- Is it best practice to configure the router loopbacks as /64's and then configure "ipv6 ospf network point-to-point" under the loopback so that the IPv6 address is advertised as a /64 and not as /128?

I think it's going to depend on what you're wanting to use the loopback for. If you're going to use it for management purposes only, I'd personally just use the /128 that it advertses by default. If you're needing to advertise a network for users to get to, and you need to do that via loopback, then you should use the point-to-point. The drawback obviously is that you have a /64 that you're advertising as a /128, so you're losing that much address space. You could set aside a few addresses within the block and advertise them as /128s as well if you're needing something more granular.

- There is no need to have "passive-interface default + no passive-interface" under address-family ipv6 unicast as you enable OSPFv3 under each Interface?

I had to test this one. Passive interfaces are still used as they were in the past. If I configured an ipv6 address on a loopback and advertised that through s0/0 to my other neighbor, the other neighbor received the route. I configured passive-interface default and then no passive-interface s0/0. My neighbor still had the loopback ipv6 route. I would recommend it to avoid having neighborships happen where they shouldn't, and to avoid ospf updates on interfaces that you don't need.

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***
New Member

Re: OSPFv3 IPv6

Thanks very much John.

New Member

OSPFv3 IPv6

We assign our loopbacks as a /128 and pull them from one /64 block.  Makes it easy to spot a loopback IP, easy check to see your /128 get propigated by pinging it remotely, and easy to set up an access list (based on that one /64) for all loopbacks network wide.

Goal with IPv6: shorter acesslists by pooling all your needs in specific blocks.

Rudy

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